This invention relates to microphone sub-assemblies for inclusion in telephones and the like, and particularly to microphone sub-assemblies which lend themselves to automated mounting procedures.
As last steps in the manufacture of a telephone handset, a fairly rigid substrate, which may comprise one or more printed circuit boards with various electronic/optical components mounted thereon, is sandwiched between two molded plastic housing halves which are snap-fitted or otherwise fastened together. These last steps are well suited for automated assembly processes using relatively simple robotic (programmed) tools. A complication in the assembly process, however, is the microphone sub-assembly which must also be mounted within the telephone handset.
In one arrangement, the microphone sub-assembly comprises a quite small circular cylinder having end ports for admitting sound to a transducer within the cylinder and a two-part molded plastic container snap-fitted around the microphone cylinder. The plastic container serves a number of roles: it encloses and protects the microphone (as well as providing one or more internal acoustic sound chambers); it provides surfaces for firm mounting of the container within the housing; and it provides a sealed exit port for wires from the microphone to a wire terminating connector which, as part of the assembly process, is snap-fitted within a mating connector on the component containing substrate.
The complication presented by the microphone sub-assembly is that it is quite difficult to assemble the sub-assembly into the handset. Thus, in addition to the steps of picking-up and properly orienting and mounting the sub-assembly, the connector at the end of the microphone wires must be inserted into its mating connector on the substrate and the microphone wires must be properly nested within the housing. If the wires are not properly nested, they can be pinched between the two housing halves when they are snap-fitted together. This, of course, causes numerous problems. Indeed, owing to the difficulty of assembling the microphone sub-assembly into the handset, this assembly is generally done by hand rather than, as preferred, by machine. This problem, among others, is addressed by the invention.